Router and sip server

ABSTRACT

A boundary node router determines whether a received packet includes a SIP message and a REGISTER message, and, if so, adds its router identifier to a REGISTER message which includes a user identifier and a user terminal identifier, sent from a user terminal, and sends the message to a SIP server. The SIP server has a user management table which stores the user terminal identifier, the router identifier of a router which serves the user terminal, and a predetermined Quality of Service type, in association with each user identifier. The SIP server extracts a user identifier, a user terminal identifier, and a router identifier from a received REGISTER message, and updates the user terminal identifier and the router identifier corresponding to the extracted user identifier, to the extracted user terminal identifier and the extracted router identifier.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to routers and Session Initiation Protocol(SIP) servers, and more specifically, to a router incorporating atechnology for controlling the Quality of Service (QoS) of packets in anInternet Protocol (IP) network and a SIP server specifying the QoS ofthe router through the IP network.

2. Description of the Related Art

As broadband access to an IP network has become widespread in recentyears, applications requiring real-time capabilities such as telephonyand live video distribution on the IP network have been increasing. TheIP network is originally configured by a best-effort network and may notbe ready for communication with near-real-time characteristics.

Technologies for assuring the QoS of a network have become important,and a variety of such technologies have been standardized. One of thosetechnologies currently used is a traffic-oriented control technologyreferred to as Differentiated Services (Diff-Serv).

In a Diff-Serv network made up of boundary nodes and interior nodes,different levels of Quality of Service are provided by relativelyvarying transfer capabilities, for instance, in accordance with aDifferentiated Services Code Point (DSCP) value specified in eachpacket. The DSCP value of an Internet Protocol Version 4 (IPv4) packetis specified in the Type of Service (ToS) field of the IPv4 header. TheDSCP value of an Internet Protocol Version 6 (IPv6) packet is specifiedin the Traffic class field of the IPv6 header.

The DSCP value can be specified initially by a user terminal of an enduser who can recognize a service. The DSCP value in each header can alsobe rewritten by a boundary node router when a certain condition is met.General conditions specified in the boundary node router include an IPaddress, a TCP port number, a UDP port number, and others.

More specifically, packets to be given higher priority are selected andmarked, and the marked packets are allowed to pass the network ahead ofthe other packets. The manner of prioritization is managed by eachrouter.

SIP has come into widespread use as a protocol of real-timecommunication such as telephony on an IP network. SIP is a signalingprotocol for establishing a session necessary for communication and forchanging and disconnecting the session. The establishment of a SIPsession includes negotiations on a service using the session, the numberof the port to be used, a communication protocol, and others.Accordingly, SIP can be easily combined with a different existingprotocol and has a high extensibility.

One technology for use in a Diff-Serv network or a SIP network asdescribed above is disclosed in patent document 1 indicated below, forinstance. The technology blocks voice communication which is notpermitted by a SIP server, by providing a firewall function which can becontrolled from a call processing server (SIP server) for accessservers, boundary node routers, and other access apparatuses provided inaccess points where a carrier network is connected, on a router basis.Patent document 1 also discloses a technology of allowing an accessapparatus provided in an access point to specify the QoS of a packetidentified by a combination of a source IP address, a destination IPaddress, a source port number, a destination port number, and others, asinstructed by the SIP server. Another technology disclosed in thedocument allows the SIP server to store information indicating whichuser terminal is served by which access apparatus, together with theInternet telephone user information stored as the user information.

A switch disclosed in patent document 2 indicated below, for instance,has a function to convert a non-SIP signal output by a non-SIP terminal,such as a PBX signal, into an SIP message, and vice versa. This functionenables communication between a non-SIP telephone and a SIP terminal.

With the technologies disclosed in patent documents 3 and 4 indicatedbelow, for instance, if a caller or a calling terminal sends a SIPprotocol message including additional information describing theintention of the caller, the server identifies a called party optimumfor the intention and establishes a SIP session accordingly.

Patent Document 3 describes that a caller-side end point generates a SIPINVITE request which includes the standard routing information in itsheader portion and the additional information on the intention of thecaller in its body portion. For instance, the header may contain theaddress of a consumer electric manufacturer, and the additionalinformation given in the body may contain keywords associated with thecaller such as “washing machine,” “service,” and “model ABC.” Inaccordance with the information, the call is directed to a salespersonskilled in answering questions about services of washing machine modelABC.

Patent Document 4 discloses a method in which a proxy server judges themost accurate address to which a call is directed, using the routinginformation specified in the INVITE message and detected voice cookieinformation. If a call is made to a customer sales division and ifdetected voice cookie information includes the name of the salespersonwho talked with the caller most recently, the proxy server automaticallydirects the call to the salesperson, not to any other salespersonavailable.

A method disclosed in patent document 5, for instance, enables mutualauthentication between a SIP client and a SIP proxy, by incorporating aKerberos security system in the message flow of the SIP signalingoperation. When the SIP proxy receives a request message from the SIPclient, the SIP proxy sends a challenge message indicating that Kerberosauthentication is necessary. In response to the message, the SIP clientsends a second request message including authentication data containinga Kerberos server ticket to the proxy. Then, the proxy authenticates aclient user.

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2003-229893

[Patent Document 2] Japanese Unexamined Patent Application PublicationNo. 2002-118594

[Patent Document 3] Japanese Unexamined Patent Application PublicationNo. 2002-335267

[Patent Document 4] Japanese Unexamined Patent Application PublicationNo. 2003-22223

[Patent Document 5] Japanese Unexamined Patent Application PublicationNo. 2003-108527

Suppose that a SIP server and a boundary node router jointly implementthe Diff-Serv function, using the conventional technologies. The SIPserver stores beforehand information indicating which boundary noderouter is connected to the Internet telephone of the corresponding user,or information correlating the address of the user terminal to theaddress of the boundary node router serving the user. Based on theinformation, the SIP server specifies the QoS requested by the user inthe boundary node router serving the user terminal.

If the boundary node router serving the user terminal is changed becauseof the movement of the user terminal to another site, the addition of anew boundary node router, a change in the network configuration, andother reasons, the QoS of the user cannot be assured. If the user uses auser terminal which is not associated with a boundary node router, thesame problem occurs.

Conventionally, each time the relationship between a user terminal and aboundary node router serving the terminal is changed by moving the userterminal or the like, the maintenance person updates the correspondingmanagement information of the SIP server. If a large amount ofinformation must be changed, the update operation will take a long time,and user QoS control cannot be specified for a certain period. An errorin the updated information may hinder correct QoS control.

SUMMARY OF THE INVENTION

Accordingly, in view of the foregoing points, it is an object of thepresent invention to provide a router and a SIP server which can providean unchanged QoS service to the user even after the user terminal ismoved. Another object of the present invention is to provide a QoSservice specified for the user even when the user uses a terminal whichis not registered in advance. A further object of the present inventionis to provide a QoS service specified for the user even after a newboundary node router is added or even after a network configuration ischanged. A still further object of the present invention is todynamically update the corresponding management information of the SIPserver if the relationship between the user terminal and the boundarynode router serving the terminal is changed.

One of the foregoing objects is achieved in one aspect of the presentinvention through the provision of a router for serving a user terminaland connecting the terminal to an IP network. The router includes afirst channel interface block for receiving a message sent from the userterminal, a determination block for analyzing the message received bythe first channel interface block and determining whether apredetermined message is received, an information addition block foradding the information of the router itself to the message if thedetermination block determines that the predetermined message isreceived, and a second channel interface block for sending thepredetermined message to which boundary node router information createdby the information addition block has been added, to the IP network.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a router for serving a userterminal and connecting the terminal to an IP network. The routerincludes a second channel interface block for receiving a message sentfrom the IP network, a determination block for analyzing the messagereceived by the second channel interface block and determining whether apredetermined message is received, an information addition block foradding the information of the router itself to the message if thedetermination block determines that the predetermined message isreceived, and a first channel interface block for sending thepredetermined message to which boundary node router information createdby the information addition block has been added, to the user terminal.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a SIP server for beingconnected to an IP network and for performing QoS control for an IPpacket of Realtime Transport Protocol (RTP) or RTP control protocol(RTCP) identified by the port number and the IP address of a userterminal. The SIP server includes a storage block for storing the routerserving position information of a user terminal, a reception block forreceiving a message sent from the router, and a serving position updateblock for updating the information of the storage block if the messagereceived by the reception block is a predetermined message.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a router for serving acommunication terminal which sends a REGISTER message including a useridentifier and a terminal identifier and for performing Quality ofService control for each user under an instruction from a server; therouter being used in a network system comprising a SIP server forstoring a terminal identifier of the communication terminal, a routeridentifier of the router serving the communication terminal, and acertain Quality of Service type, in association with the useridentifier, and for instructing the router identified by thecorresponding router identifier to perform Quality of Service control inaccordance with the Quality of Service type corresponding to the useridentifier or the terminal identifier; the router comprising: means forjudging whether a received packet or a received message is a SIPmessage; means for analyzing and determining whether the message judgedto be a SIP message is a REGISTER message, for adding the routeridentifier of the local router to the REGISTER message including theuser identifier and terminal identifier given by the communicationterminal if the message is a SIP message and a REGISTER message, and fortransferring the REGISTER message including the added router identifierto the SIP server so that the terminal identifier and router identifierstored in association with the user identifier are updated in the SIPserver; means for receiving a Quality of Service control instructioncorresponding to the Quality of Service type associated with the useridentifier or the updated terminal identifier, from the SIP server; andmeans for performing Quality of Service control for each user under thereceived instruction.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a router for serving acommunication terminal which sends, in response to an instructionmessage given for authentication, a REGISTER message including a useridentifier, a terminal identifier, and a router identifier included inthe instruction message and for performing Quality of Service controlfor each user under an instruction from a server; the router being usedin a network system comprising a SIP server for storing a terminalidentifier of the communication terminal, a router identifier of therouter serving the communication terminal, and a certain Quality ofService type, in association with the user identifier, for instructingthe router identified by the corresponding router identifier to performQuality of Service control in accordance with the Quality of Servicetype corresponding to the user identifier or the terminal identifier,and for sending an instruction message for authentication to thecommunication terminal; the router comprising: means for judging whethera received packet or a received message is a SIP message; means foranalyzing and determining whether the message judged to be a SIP messageis an instruction message, for adding the router identifier of the localrouter to the instruction message or updating the router identifierincluded in the instruction message to the router identifier of thelocal router, if the message is a SIP message and an instructionmessage, and for transferring the instruction message including theadded or updated router identifier to the communication terminal so asto make the communication terminal send a REGISTER message and to updatethe terminal identifier and the router identifier stored in associationwith the user identifier in the SIP server; means for receiving aQuality of Service control instruction corresponding to the Quality ofService type associated with the user identifier or the updated terminalidentifier, from the SIP server; and means for performing Quality ofService control for each user under the received instruction.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a SIP server for managing theQuality of Service type of each user and for instructing a routerserving a communication terminal to perform Quality of Service controlin accordance with the Quality of Service type of each user, and the SIPserver is used in a network system which includes the router, the routerserving a communication terminal which sends a REGISTER messageincluding a user identifier and a terminal identifier to be used or acommunication terminal which sends, in response to an instructionmessage given for authentication, a REGISTER message including a useridentifier, a terminal identifier, and a router identifier included inthe instruction message, and performing Quality of Service control foreach user under an instruction from a server. The SIP server includes atable for storing a terminal identifier of the communication terminal, arouter identifier of the router serving the communication terminal, anda certain Quality of Service type, in association with the useridentifier; means for analyzing a received message and determiningwhether the message is a REGISTER message; means for extracting a useridentifier, a terminal identifier, and a router identifier, if themessage is a REGISTER message, from a REGISTER message generated whenthe router has added the router identifier of the router to the REGISTERmessage including the user identifier and the terminal identifier givenby the communication terminal or from a REGISTER message sent from thecommunication terminal in response to an instruction message to whichthe router has added or updated the router identifier, sent from theserver to the communication terminal, for referencing the table inaccordance with the extracted user identifier, and for updating theterminal identifier and the router identifier associated with thecorresponding user identifier to the extracted terminal identifier andthe extracted router identifier; and means for instructing the routeridentified by the updated router identifier to perform Quality ofService control in accordance with a Quality of Service type associatedwith the user identifier or the updated terminal identifier, withreference to the table.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a network system including arouter for serving a communication terminal which sends a REGISTERmessage including a user identifier and a terminal identifier and forperforming Quality of Service control for each user under an instructionfrom a server, and a SIP server for managing the Quality of Service typeof each user and for instructing the router serving the communicationterminal to perform Quality of Service control in accordance with theQuality of Service type of each user. The router includes means forjudging whether a received packet or a received message is a SIPmessage; means for analyzing and determining whether the message judgedto be an SIP message is a REGISTER message, for adding the routeridentifier of the local router to the REGISTER message including theuser identifier and terminal identifier given by the communicationterminal if the message is a SIP message and a REGISTER message, and fortransferring the REGISTER message with the router identifier added tothe SIP server so that the terminal identifier and router identifierstored in association with the user identifier are updated in the SIPserver; means for receiving a Quality of Service control instructioncorresponding to the Quality of Service type associated with the useridentifier or the updated terminal identifier, from the SIP server; andmeans for performing Quality of Service control for each user under thereceived instruction. The SIP server includes a table for storing aterminal identifier of the communication terminal, a router identifierof the router serving the communication terminal, and a certain Qualityof Service type, in association with the user identifier; means foranalyzing a received message and determining whether the message is aREGISTER message; means for extracting a user identifier, a terminal,identifier, and a router identifier, if the message is a REGISTERmessage, from a REGISTER message generated when the router has added therouter identifier of the router to the REGISTER message including theuser identifier and the terminal identifier given by the communicationterminal, for referencing the table in accordance with the extracteduser identifier, and for updating the terminal identifier and the routeridentifier associated with the corresponding user identifier to theextracted terminal identifier and the extracted router identifier; andmeans for instructing the router identified by the updated routeridentifier to perform Quality of Service control in accordance with aQuality of Service type associated with the user identifier or theupdated terminal identifier, with reference to the table.

One of the foregoing objects is achieved in another aspect of thepresent invention through the provision of a network system including arouter for serving a communication terminal which sends, in response toan instruction message given for authentication, a REGISTER messageincluding a user identifier, a terminal identifier to be used, and arouter identifier included in the instruction message and for performingQuality of Service control for each user under an instruction from aserver, and a SIP server for managing the Quality of Service type ofeach user, for instructing the router serving the communication terminalto perform Quality of Service control in accordance with the Quality ofService type of each user, and for sending an instruction message forauthentication to the communication terminal. The router includes meansfor judging whether a received packet or a received message is a SIPmessage; means for analyzing and determining whether the message judgedto be a SIP message is an instruction message, for adding the routeridentifier of the local router to the instruction message or updatingthe router identifier included in the instruction message to the routeridentifier of the local router if the message is a SIP message and aninstruction message, and for transferring the instruction messageincluding the added or updated router identifier to the communicationterminal so as to make the communication terminal send a REGISTERmessage and to update the terminal identifier and the router identifierstored in association with the user identifier in the SIP server; meansfor receiving a Quality of Service control instruction corresponding tothe Quality of Service type associated with the user identifier or theupdated terminal identifier, from the SIP server; and means forperforming Quality of Service control for each user under the receivedinstruction. The SIP server includes a table for storing a terminalidentifier of the communication terminal, a router identifier of therouter serving the communication terminal, and a certain Quality ofService type, in association with the user identifier; means foranalyzing a received message and determining whether the message is aREGISTER message; means for extracting a user identifier, a terminalidentifier, and a router identifier, if the message is a REGISTERmessage, from a REGISTER message sent from the communication terminal inresponse to an instruction message to which the router has added orupdated the router identifier of the router, sent from the server to thecommunication terminal, for referencing the table in accordance with theextracted user identifier, and for updating the terminal identifier andthe router identifier associated with the corresponding user identifierto the extracted terminal identifier and the extracted routeridentifier; and means for instructing the router identified by theupdated router identifier to perform Quality of Service control inaccordance with the Quality of Service type associated with the useridentifier or the updated terminal identifier, with reference to thetable.

The present invention can provide a network system, a SIP server, and arouter which can provide an unchanged QoS service to the user even ifthe user terminal is moved. The present invention enables a QoS servicespecified for the user to be provided even when the user uses anon-registered terminal. With the present invention, a QoS servicespecified for the user can be provided even if a new boundary noderouter is added or even if the network configuration is changed. Thepresent invention enables dynamic updating of the correspondingmanagement information of the SIP server when the relationship betweenthe user terminal and the boundary node router serving the terminalchanges.

With the present invention, if a user terminal is moved or added in anetwork where a SIP server and a boundary node router jointly implementQoS control, the SIP server can dynamically identify the router servingthe user terminal. When the user position is stored in accordance with aREGISTER message sent by the user terminal, the stored information ofrelationship between the user terminal and the boundary node routerserving the user terminal can be automatically updated in the SIPserver. Accordingly, the SIP server makes the same QoS setting for thesame user, either with the previous boundary node router or with the newboundary node router. Even when the user terminal is moved, an unchangedQoS service can be provided for the user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the configuration of a network in a firstembodiment.

FIG. 2 shows a block diagram of a boundary node router of the firstembodiment.

FIG. 3 shows a block diagram of a control block in the boundary noderouter of the first embodiment.

FIG. 4 shows a block diagram of a protocol processing block in theboundary node router of the first embodiment.

FIG. 5 is a view showing the header of a REGISTER message.

FIG. 6 is a view showing the header of another REGISTER message.

FIG. 7 shows a block diagram of a SIP server of the first embodiment.

FIG. 8 is a view showing the configuration of a user management table ofthe first embodiment.

FIG. 9 is a view showing the configuration of another network of thefirst embodiment.

FIG. 10 is a view showing the configuration of a user management tableof the first embodiment.

FIG. 11 shows a flowchart of the processing of the boundary node routerin the first embodiment.

FIG. 12 shows a flowchart of the processing of the SIP server in thefirst embodiment.

FIG. 13 shows a conventional SIP authentication sequence.

FIG. 14 shows a SIP authentication sequence of a second embodiment.

FIG. 15 is a flowchart of the processing of a boundary node router inthe second embodiment.

FIG. 16 is a view showing the header of an Unauthorized message.

FIG. 17 is a view showing the header of another Unauthorized message.

FIG. 18 is a view showing the header of a REGISTER message.

FIG. 19 is a view showing the header of another REGISTER message.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below.

1. First Embodiment

(Apparatus Configuration)

FIG. 1 is a view showing the configuration of a Diff-Serv network. TheDiff-Serv network includes boundary node routers 2-1, 2-2, and 2-3(collectively called a boundary node router 2), interior node routers4-1 and 4-2 (collectively called an interior node router 4), and a SIPserver 1.

The boundary node router 2 is disposed on a border between the Diff-Servnetwork and another network such as an access network. The boundary noderouter assigns a DSCP value and performs QoS control based on the DSCPvalue and others. The boundary node router 2 serves a user terminal(communication terminal) which sends at least a REGISTER messageincluding a network user identifier and a user terminal identifier,through an access network. The boundary node router 2 performs QoScontrol for each user in accordance with a QoS control request from theSIP server 1.

The interior node router 4 is disposed in the Diff-Serv network andperforms QoS control based on the DSCP value.

The SIP server 1 supports session establishment based on a SIP message.The SIP server 1 also gives the boundary node router 2 a QoS controlrequest for each user. The SIP server 1 has a management table storingthe QoS types of the individual users and can make a QoS control requestfor each user with reference to the management table. The configurationof the management table will be described later in further detail.

In FIG. 1, the SIP server 1 has a proxy server function, a redirectserver function, and a register server function, for ease ofexplanation. These functions may be implemented by separate apparatusesor servers. The separate servers should exchange information with oneanother under the SIP protocol.

In the configuration shown in FIG. 1, each user name is described in theformat of “account@domain”. User A having a user name of userA@left.netuses user terminal A 3-1 at 10.10.10.10, and user terminal A 3-1 isconnected to boundary node router A 2-1 at 192.168.10.1 through accessnetwork A. In this configuration, the terminals and routers use IPaddresses, and user names are SIP URIs.

User C using a user name of userc@right.net uses user terminal C 3-3 at10.10.30.10, and user terminal C 3-3 is connected to boundary noderouter C 2-3 at 10.12.34.5 through access network C. When the SIP server1 establishes a session, user A and user C can communicate with givenQoS, through boundary node router A 2-1, interior node routers A 4-1 andB 4-2, and boundary node router C 2-3, for instance. The accounts andaddresses listed here are examples, and actual accounts and addressesmay be different.

FIG. 2 shows a block diagram of the boundary node router 2.

The boundary node router 2 includes protocol processing blocks 20-1 to20-n, channel interface blocks 21-1 to 21-n, an internal switch 30, anda control block 40.

The channel interface block 21 functions as a physical interface with anetwork. The internal switch 30 performs packet switching betweeninterfaces. The control block 40 controls the whole apparatus, and addsthe identifier of the router itself to a certain message. The protocolprocessing block 20 transfers a received packet and determines whetherthe received packet is a SIP message. The determination of the SIPmessage and the addition of the router identifier may be performed by anappropriate processing block in the boundary node router.

The boundary node router 2 has a connection interface with a settingterminal 50, in addition to the channel interface 21. The settingterminal 50 can be connected to the control block 40 and can makesettings of the boundary node router 2.

FIG. 3 shows a block diagram of the control block 40 in the boundarynode router 2. The control block 40 includes a CPU 403, a memory 401,and a processor-to-processor communication interface 404. A settingterminal interface 402 may also be included.

The CPU 403 executes processing. The memory 401 stores a processingprogram and internal data. The processor-to-processor communicationinterface 404 is an interface for enabling communication with theprocessor of the protocol processing block 20, which will be describedlater. The setting terminal interface 402 is an interface for enablingconnection to the setting terminal 50.

The memory 401 includes an apparatus-status management block 4011, aSIP-message computation block 4012, and a routing computation block4013.

The apparatus-status management block 4011 manages apparatus statusessuch as alarm generation and open/close statuses of channel interfaces.The SIP-message computation block 4012 updates or changes the header ofa given SIP message. The routing computation block 4013 transfers aninstruction to update the routing information from the setting terminal50, for instance, to the protocol processing block 20. The blocks in thememory 401 are loaded and executed by the CPU 403.

FIG. 4 shows a block diagram of the protocol processing block 20 in theboundary node router 2.

The protocol processing block 20 includes a protocol processingprocessor 201, a channel-interface-side transmission buffer 202, achannel-interface-side reception buffer 203, an internal-switch-sidetransmission buffer 204, an internal-switch-side reception buffer 205, amemory 207, and a processor-to-processor communication interface 206.

The protocol processing processor 201 executes processing. Thechannel-interface-side transmission buffer 202 is a buffer for holding apacket to be sent from the protocol processing processor 201 to thechannel interface block 21. The channel-interface-side reception buffer203 is a buffer for holding a packet to be sent from the channelinterface blocks 21 to the protocol processing processor 201. Theinternal-switch-side transmission buffer 204 is a buffer for holding apacket to be sent from the protocol processing processor 201 to theinternal switch 30. The internal-switch-side reception buffer 205 is abuffer for holding a packet to be sent from the internal switch 30 tothe protocol processing processor 201. The processor-to-processorcommunication interface 206 is an interface for enabling communicationwith the CPU 403 of the control block 40.

The memory 207 stores a processing program and internal data. The memory207 includes a packet transfer block 2071, a routing registration block2072, a routing table 2073, an address analysis block 2074, and amessage analysis block 2075, for instance.

The message analysis block 2075 analyzes the contents of a receivedpacket and determines whether the packet is a SIP message. The packettransfer block 2071 locates a transfer destination on the basis of theaddress included in the packet and the information in the routing table2073, and transfers the packet accordingly. The routing registrationblock 2072 incorporates updated routing information sent from therouting computation block 4013 of the control block 40, into the routingtable 2073. The routing table 2073 holds the routing information. Theaddress analysis block 2074 extracts an address from a received packetand makes an analysis. The blocks in the memory 207 are loaded andexecuted by the protocol processing processor 201.

The message analysis block 2075 and the SIP-message computation block4012 are included in the protocol processing block 20 and the controlblock 40 respectively, but both of the blocks may be included in eitherthe protocol processing block 20 or the control block 40.

The boundary node router 2 can further include means for receiving fromthe SIP server 1 a QoS control instruction depending on the QoS typespecified for the user identifier or the updated terminal identifier andmeans for executing QoS control for each user in accordance with thereceived instruction. These means can be provided in either the controlblock 40 or the internal switch 30.

FIG. 7 shows a block diagram of the SIP server 1.

The SIP server 1 includes a channel interface block 11, a CPU 101, and amemory 102. The channel interface block 11 serves a channel. The CPU 101controls the entire apparatus and executes processing. The memory 102stores a processing program and internal data.

The memory 102 includes a SIP-message analysis block 1021 and a usermanagement table 1023. The SIP-message analysis block 1021 analyzes areceived SIP message and determines whether the message is a REGISTERmessage or an Unauthorized message, for instance. The SIP-messageanalysis block 1021 can also manage user information and otherinformation. The user management table 1023 stores the router servingposition information and information for QoS control, of individualusers. In the user management table 1023, a user name, a user IPaddress, a router IP address of a router serving the user terminal, anda QoS type are associated with each other and stored. The block in thememory 102 is loaded and executed by the CPU 101.

The SIP server 1 can also have means for instructing the router 2identified by an updated router identifier to perform QoS control inaccordance with the QoS type corresponding to the user identifier or theupdated terminal identifier, with reference to the user management table1023.

(Table Configuration)

FIG. 8 shows a sample configuration of the user management table 1023 inthe SIP server 1. In the user management table 1023, a user terminaladdress 10232, a boundary node router address 10233 of a boundary noderouter serving the user terminal, and a QoS type 10234 are specified inadvance in association with a user name 10231. The user name can be SIPURI, and the user terminal address and the router address can be an IPaddress.

The table shown in FIG. 8 lists the information of the networkconfiguration shown in FIG. 1. For instance, user A having a user nameof userA@left.net, user terminal A at 10.10.10.10, and boundary noderouter A 2-1 at 192.168.10.1 are correlated, and QoS type 1 is specifiedfor this combination.

User C having a user name of userC@right.net, user terminal C at10.10.30.10, and boundary node router C 2-3 at 10.12.34.5 arecorrelated, and QoS type 1 is specified for this combination. Theseinformation items can be specified by the maintenance person when asubscription starts or when an address is changed.

The CPU 101 in the SIP server 1 recognizes the QoS type specified in thetable 1023 and specifies QoS of the corresponding boundary node router.Then, user A and user C can communicate with given QoS (QoS type 1, inthe shown example).

The shown table indicates that the same QoS type is specified for bothuser A and user C. However, the individual boundary node routers mayhave different QoS settings.

FIG. 9 is a view showing that user terminal A 3-1 in FIG. 1 is moved andconnected through access network B to boundary node router B 2-2 at172.21.20.1 and is going to communicate with user terminal C 3-3. Afterthe movement, the address of user terminal A is changed to 10.10.20.10.

The user management table of the SIP server 1 must be updated inaccordance with an update instruction from the boundary node routerserving user terminal A 3-1. Otherwise, the SIP server 1 would make aQoS control request to the router before the movement, and user A wouldnot be given the same QoS service as shown in FIG. 1.

(Processing Flow)

FIG. 11 shows a flowchart of processing performed when the boundary noderouter of the first embodiment receives a packet. FIG. 12 shows aflowchart of processing performed when the SIP server 1 receives a SIPmessage from the user terminal 3. With reference to FIGS. 11 and 12, theprocessing to update the user management table 1023 in the SIP server 1will be described next.

The user terminal 3 sends a REGISTER message including the user ID andthe user terminal ID, to the SIP server 1, at initialization andperiodically.

The message analysis block 2075 in the protocol processing block 20 ofthe boundary node router 2 analyzes the received packet and checkswhether the received packet is a SIP message (step S50). For instance,when the protocol processing processor 201 receives a packet, themessage analysis block 2075 checks whether the received packet is a SIPmessage. If the received packet is not a SIP message, the processinggoes to step S54. If the received packet is a SIP message, the protocolprocessing block 20 transfers the SIP message through theprocessor-to-processor communication interface 206 to the control block40. The protocol processing processor 201 can manage the processing ofeach block in memory 207.

The control block 40 receives the SIP message transferred from theprotocol processing block 20 via the processor-to-processorcommunication interface 404, and the SIP-message computation block 4012checks whether the transferred message is a REGISTER message (step S51).For instance, the SIP-message computation block 4012 analyzes the SIPmessage and determines whether a message type indicates REGISTER. If theSIP message is made up of a plurality of packets, the SIP-messagecomputation block 4012 may analyze the message after a certain number ofpackets are accumulated.

If the transferred message is not a REGISTER message, the SIP-messagecomputation block 4012 returns the packet through theprocessor-to-processor communication interface 404 to the protocolprocessing block 20, and the processing goes to step S54.

If the transferred message is a REGISTER message, the SIP-messagecomputation block 4012 further analyzes the header of the REGISTERmessage and checks whether the information of a boundary node router isincluded (step S52). If the header of the REGISTER message containsboundary node router information, which is given by another boundarynode router 2, the SIP-message computation block 4012 returns the packetthrough the processor-to-processor communication interface 404 to theprotocol processing block 20, and the processing goes to step S54. Ifthe header of the REGISTER message contains boundary node routerinformation, the local router is not a boundary node router serving theuser terminal.

If the header of the REGISTER message does not contain boundary noderouter information, the SIP-message computation block 4012 adds theaddress of the local router as the address of the boundary node routerserving the user terminal 3, to the header of the REGISTER message (stepS53), and the processing goes to step S54. If the header of the REGISTERmessage does not contain boundary node router information, the localrouter is the boundary node router 2 serving the user terminal. Bychecking the presence or absence of the boundary node router informationin step S52, the addition of redundant boundary node router informationcan be avoided when the message is transferred through a plurality ofrouters of this embodiment.

In step S54, the packet transfer block 2071 transfers a non-SIP messageand a packet returned from the SIP-message computation block 4012, tothe next network in the same way as in a usual router.

The addition of information by the SIP-message computation block 4012will be described next in further detail, with reference to FIGS. 5 and6.

FIG. 5 is a view showing the header 7 of a REGISTER message which issent from the user terminal 3 and received by the boundary node router2. The header 7 includes a message type 70, a user address 71, and auser-terminal address 72. FIG. 6 is a view showing the header 7 of aREGISTER message, to which the boundary node router information 73 isadded by the SIP-message computation block 4012.

The SIP-message computation block 4012 analyzes the header 7 of themessage sent from the user terminal 3 and judges from the message type70 whether the message is a REGISTER message. The SIP-messagecomputation block 4012 adds boundary node router information 73 such asthe local IP address to the REGISTER message, as shown in FIG. 6 (stepS53 in FIG. 11).

If the user terminal 3 is moved as shown in FIG. 9, for instance,boundary node router B 2-2 adds address 172.21.20.1 of itself to theheader 7 of the REGISTER message sent by the user terminal 3.

The element of the header information to be added here may be either anew element or an existing element that can be recognized by the SIPserver and the boundary node router. In FIG. 6, a new header informationelement, QoS-Router, is added.

For instance, the address of boundary node router B 2-2 can be added byusing an existing header information element, as described below. If theError-Info element in the header of the REGISTER message is used to addaddress 172.21.20.1 of boundary node router B 2-2, the element can bespecified as “Error-Info: BoundaryRouterB<172.21.20.1>”, and the messagewith the updated header should be sent to the SIP server 1. The Warningelement or another appropriate header information element can also beused in the same manner.

FIG. 12 is a flowchart of processing performed when the SIP server 1receives a SIP message from the user terminal 3.

When the SIP server 1 or the CPU 101 receives a packet or a message sentvia the channel interface block 11, the SIP-message analysis block 1021analyzes the received packet or message and determines whether thepacket or message is a REGISTER message of the SIP protocol (step S60).

If the SIP-message analysis block 1021 determines that the receivedmessage is not a REGISTER message, the processing goes to step S64.

If the received message is a REGISTER message, the SIP-message analysisblock 1021 checks the information in the header of the REGISTER messageto see whether the boundary node router information 73 of the routerserving the user terminal is included (step S61). The SIP-messageanalysis block 1021 checks whether the header of the message includesQoS-Router, Error-Info specified to add boundary node routerinformation, or another element.

If the SIP-message analysis block 1021 cannot find the boundary noderouter information 73, the processing goes to step S64. If the boundarynode router information 73 is found, the SIP-message analysis block 1021checks whether the user management table 1023 includes the informationof the user sending the SIP message (step S62). For instance, theSIP-message analysis block 1021 extracts the user name 71 (SIP URI, forinstance) from the header of the message, and searches through the username field of the user management table 1023 for the corresponding username.

If the SIP-message analysis block 1021 cannot find the correspondinguser name, the processing goes to step S64. If the corresponding username is found, the SIP-message analysis block 1021 updates the usermanagement table 1023 in which the address of the user terminal 3 usedby the user and the address of the boundary node router serving the userterminal 3 are associated (step S63), and the processing goes to stepS64. More specifically, the SIP-message analysis block 1021 extracts theuser terminal address 72 and the boundary node router information 73from the REGISTER message. Then, the SIP-message analysis block 1021rewrites the user terminal IP address 10232 and the boundary node routerIP address 10233 associated with the user name in the user managementtable 1023, to the extracted user terminal address 72 and the extractedboundary node router information 73.

In step S64, the SIP-message analysis block 1021 performs normal messagereception processing. If the processing of step S63 has been executed,the processing of step S64 may be omitted and the sequence may beterminated.

FIG. 10 shows a configuration of the updated table. The user managementtable 1023 of the SIP server 1 contains information, as shown in FIG. 8.If the user name of moved user A is found in the table, thecorresponding user terminal address and boundary node router address arerewritten.

If user terminal A 3-1 is moved and if the address of the user terminalis changed, as shown in FIG. 9, the user terminal address correspondingto user A having a user name of userA@left.net is changed from10.10.10.10 to 10.10.20.10. The corresponding boundary node routeraddress is changed from the address 192.168.10.1 of boundary node routerA 2-1 to address 172.21.20.1 of boundary node router B 2-2. These piecesof information are included in the header 7 of the REGISTER message sentfrom the boundary node router 2.

The movement also changes the user terminal address, and the change canbe incorporated by a known technology: Generally, the changed address isautomatically assigned by a DHCP server in the access network and isrecognized by the user terminal.

The SIP server 1 checks the updated user management table 1023 and givesthe router identified by the corresponding router identifier aninstruction to perform QoS control in accordance with the QoS typecorresponding to the user identifier or the user terminal identifier.

When user A moves user terminal A 3-1 from boundary node router A 2-1 toboundary node router B 2-2 and wants to establish a SIP session throughboundary node router B 2-2, the SIP server 1 references the usermanagement table 1023 and specifies the QoS of boundary node router B2-2 so that the same QoS service as provided by boundary node router A2-1 (QoS 1, in this example) can be provided. Then, user terminal A 3-1can receive the same QoS service as provided before the movement.

Accordingly, even if the user terminal 3 is moved, an unchanged QoSservice can be provided by dynamically rewriting the table in the SIPserver 1, without manually updating data in the SIP server 1 as a partof maintenance.

2. Second Embodiment

The boundary node router 2 of the first embodiment described abovechecks a message received from the user terminal 3, adds certaininformation to the message, and transfers the message to the SIP server1, to update information in the SIP server 1. A boundary node router 2of a second embodiment checks a message received from a SIP server 1,adds certain information to the message, and transfers the message to auser terminal 3, to update information in the SIP server 1 from the userterminal 3.

The second embodiment uses the same apparatus configuration and the sametable configuration as the first embodiment described above, and thedescription of those configurations will be omitted.

FIG. 13 shows a typical message sequence for terminal authentication bythe SIP protocol. First, the normal terminal authentication sequencewill be described.

User terminal A 3-1 to be served by the SIP server 1 sends a REGISTERmessage which does not include certain authentication information, viaboundary node router A 2-1 to the SIP server 1 (step S131). The SIPserver 1 confirms that the REGISTER message does not includeauthentication information, and returns a 401 Unauthorized message(instruction message) including a nonce value, a realm value, and otherauthentication information to user terminal A 3-1, encouraging theexecution of digest authentication (step S 132). The 401 Unauthorizedmessage from the SIP server 1 is sent via boundary node router A 2-1 touser terminal A 3-1.

In response to the 401 Unauthorized message received from the SIP server1, user terminal A 3-1 sends another REGISTER message to the SIP server1, using the nonce value and the realm value included in the receivedmessage (step S133). The user terminal 3 is specified in advance to senda REGISTER message in response to the 401 Unauthorized message. Userterminal A 3-1 may specify the user ID and password (authenticationinformation) and incorporate the information into the REGISTER message,in steps S131 or S133.

The SIP server 1 checks whether the authentication information in thereceived message matches stored authentication information, forinstance. If the authentication is successful, the SIP server 1 sends a200 OK message to user terminal A 3-1 (step S134). Terminalauthentication by SIP is generally performed as described above.

FIG. 14 shows a message sequence for terminal authentication by the SIPprotocol and for updating the user management table, according to thepresent embodiment.

User terminal A 3-1 to be served by the SIP server 1 sends a REGISTERmessage which does not include authentication information, via boundarynode router A 2-1 to the SIP server 1 (step S141), as in step S131,described above. In this embodiment, the boundary node router 2 receivesthe REGISTER message and transfers the message to the SIP server 1, justlike a normal packet or message.

The SIP server 1 receives the REGISTER message and confirms that themessage does not include authentication information, and returns a 401Unauthorized message including a nonce value, a realm value, and othersto user terminal A 3-1, encouraging the execution of digestauthentication (step S142).

Boundary node router A 2-1 of this embodiment checks all the passingpackets and messages. When the 401 Unauthorized message passes, boundarynode router A 2-1 executes processing shown in FIG. 15, which will bedescribed later, and adds boundary node router information to the 401Unauthorized message (step S143). Boundary node router A 2-1 also sendsthe 401 Unauthorized message with boundary node router information addedto user terminal A 3-1 (step S144).

User terminal A 3-1 receives the 401 Unauthorized message from the SIPserver 1 via boundary node router A 2-1 and sends another REGISTERmessage to the SIP server 1 (step S145), using the nonce value, therealm value, and other boundary node router information included in thereceived message. In this embodiment, the boundary node routerinformation added by boundary node router A 2-1 is added to the headerof the REGISTER message to be sent. User terminal A 3-1 may specify auser ID and a password and include these items in the REGISTER messagesent in step S141 or S145.

The SIP server 1 checks whether the authentication information in thereceived message matches stored authentication information, forinstance. If the authentication is successful, the same processing asperformed for the first embodiment is performed, as shown in FIG. 12,for instance. The corresponding user terminal address and thecorresponding boundary node router address are rewritten in the usermanagement table 1023 (step S146). Then, the SIP server 1 returns a 200OK message to user terminal A 3-1 (step S147).

FIG. 15 is a flowchart of processing performed when the boundary noderouter 2 receives a packet.

When the boundary node router 2 receives a packet, a message analysisblock 2075 in a protocol processing block 20 checks the received packetand judges whether the received packet includes a SIP message (stepS70). For instance, when a protocol processing processor 201 receives apacket, the message analysis block 2075 checks whether the receivedpacket includes a SIP message. If the received packet does not include aSIP message, the processing goes to step S74. If the received packetincludes a SIP message, the protocol processing block 20 transfers theSIP message via a processor-to-processor communication interface 206 toa control block 40. The protocol processing processor 201 can manage theprocessing of blocks in a memory 207.

The control block 40 receives the SIP message transferred from theprotocol processing block 20 via a processor-to-processor communicationinterface 404, and a SIP-message computation block 4012 checks whetherthe transferred message is a 401 Unauthorized message (step S71). Forinstance, the SIP-message computation block 4012 analyzes the SIPmessage and checks whether the message is a REGISTER message. If the SIPmessage is made up of a plurality of packets, the SIP-messagecomputation block 4012 may analyze the message after a certain number ofpackets are accumulated.

If the transferred message is not a 401 Unauthorized message, theSIP-message computation block 4012 returns the packet through theprocessor-to-processor communication interface 404 to the protocolprocessing block 20, and the processing goes to step S74. If thetransferred message is a 401 Unauthorized message, the SIP-messagecomputation block 4012 further analyzes the header of the 401Unauthorized message and checks whether boundary node router informationis included (step S72).

If the header of the REGISTER message contains the boundary node routerinformation given by a different boundary node router 2, the SIP-messagecomputation block 4012 updates or changes the boundary node routerinformation to the local router identifier (step S75), and theprocessing goes to step S74. If the header of a message containsboundary node router information, the local router is closer to the userthan the different boundary node router.

If the header of the 401 Unauthorized message contains no boundary noderouter information, the SIP-message computation block 4012 adds theaddress of the local router to the header of the 401 Unauthorizedmessage, as the address of the boundary node router serving the userterminal 3 (step S73), and the processing goes to step S74.

In step S74, the packet transfer block 2071 transfers the receivedpacket to the next network, as in a normal router.

The addition and update of certain information will be described infurther detail, with reference to FIGS. 16 to 19. FIG. 16 is a viewshowing the header of a 401 Unauthorized message 142 sent from the SIPserver 1 and received by the boundary node router 3 (message sent instep S142, for instance). The header includes a message type 160, a username 161, and others.

If the message is judged to be a 401 Unauthorized message after theanalysis of the header shown in FIG. 16, boundary node router A 2-1 addsboundary node router information such as the IP address of the localrouter (step S73 in FIG. 15) and sends the message to user terminal A3-1.

FIG. 17 is a view showing an example of a 401 Unauthorized message 144with boundary node router information 163 added. If user terminal A 3-1is moved as shown in FIG. 9, the address 172.21.20.1 of boundary noderouter B 2-2 is added or updated in the header of the 401 Unauthorizedmessage 144 sent by user terminal A 3-1.

The element of header information to be added here may be either a newheader information element or an existing header information elementthat can be recognized by the SIP server and the boundary node router. Anew header information element, QoS-Router 163, is added in FIG. 17.

FIG. 18 is a view showing the header of a REGISTER message 133 sent byuser terminal A 3-1 and received by the SIP server 1 (a message sent instep S133, for instance). The header includes a message type 180, a useraddress 181, a user terminal address 182, and others.

FIG. 19 is a view showing the header of a REGISTER message 145 sent byuser terminal A 2-1 (a message sent in step S145, for instance) whichhas received the 401 Unauthorized message with the boundary node routerinformation 183 added by boundary node router A 2-1.

The headers shown in FIGS. 18 and 19 are different in that the boundarynode router information 183 added by boundary node router A 3-1 isreturned. More specifically, the boundary node router information 183(IP address of the boundary node router) is added or updated in theheader shown in FIG. 19. The user management table 1023 of the SIPserver 1 is updated in accordance with the user terminal address 182 andthe boundary node router information 183 included in the REGISTERmessage 145 from the user terminal.

When user A moves user terminal A 3-1 from boundary node router A 2-1 toboundary node router B 2-2 and wants to establish a SIP session throughboundary node router B 2-2, as in the first embodiment, the SIP server 1specifies the QoS type of boundary node router B 2-2, which serves userterminal A 3-1, so that the same QoS service as provided by boundarynode router A 2-1 (QoS type 1 in this example) can be provided.Accordingly, user terminal A 3-1 can receive the same QoS service asprovided before the movement.

Even if the user terminal 3 is moved, an unchanged QoS service can beprovided by dynamically rewriting the table in the SIP server 1, withoutmanually updating data in the SIP server 1 as a part of maintenance.

The first and second embodiments have been described by taking anexample of moving a user terminal to a different router. The sameapplies when the address information of a user terminal changes. Theaddress information of a user terminal changes when the user uses adifferent terminal, when the address of the user terminal changes, andin some other cases.

1. A router for serving a communication terminal which sends a REGISTERmessage including a user identifier and a terminal identifier and forperforming Quality of Service control for each user under an instructionfrom a server; the router being used in a network system comprising aSIP server for storing a terminal identifier of the communicationterminal, a router identifier of the router serving the communicationterminal, and a certain Quality of Service type, in association with theuser identifier, and for instructing the router identified by thecorresponding router identifier to perform Quality of Service control inaccordance with the Quality of Service type corresponding to the useridentifier or the terminal identifier; the router comprising: means forjudging whether a received packet or a received message is a SIPmessage; means for analyzing and determining whether the message judgedto be a SIP message is a REGISTER message, for adding the routeridentifier of the local router to the REGISTER message including theuser identifier and terminal identifier given by the communicationterminal if the message is a SIP message and a REGISTER message, and fortransferring the REGISTER message including the added router identifierto the SIP server so that the terminal identifier and router identifierstored in association with the user identifier are updated in the SIPserver; means for receiving a Quality of Service control instructioncorresponding to the Quality of Service type associated with the useridentifier or the updated terminal identifier, from the SIP server; andmeans for performing Quality of Service control for each user under thereceived instruction.
 2. A router for serving a communication terminalwhich sends, in response to an instruction message given forauthentication, a REGISTER message including a user identifier, aterminal identifier, and a router identifier included in the instructionmessage and for performing Quality of Service control for each userunder an instruction from a server; the router being used in a networksystem comprising a SIP server for storing a terminal identifier of thecommunication terminal, a router identifier of the router serving thecommunication terminal, and a certain Quality of Service type, inassociation with the user identifier, for instructing the routeridentified by the corresponding router identifier to perform Quality ofService control in accordance with the Quality of Service typecorresponding to the user identifier or the terminal identifier, and forsending an instruction message for authentication to the communicationterminal; the router comprising: means for judging whether a receivedpacket or a received message is a SIP message; means for analyzing anddetermining whether the message judged to be a SIP message is aninstruction message, for adding the router identifier of the localrouter to the instruction message or updating the router identifierincluded in the instruction message to the router identifier of thelocal router, if the message is a SIP message and an instructionmessage, and for transferring the instruction message including theadded or updated router identifier to the communication terminal so asto make the communication terminal send a REGISTER message and to updatethe terminal identifier and the router identifier stored in associationwith the user identifier in the SIP server; means for receiving aQuality of Service control instruction corresponding to the Quality ofService type associated with the user identifier or the updated terminalidentifier, from the SIP server; and means for performing Quality ofService control for each user under the received instruction.
 3. Arouter according to claim 2, wherein the instruction message is anUnauthorized message.
 4. A router according to one of claims 1 and 2,wherein the transfer means creates a new additional information headerincluding the router identifier of the local router and adds the createdadditional information header to a message or updates the header to thecreated additional information header, or adds the router identifier ofthe local router to a preselected header or updates the routeridentifier in the preselected header.
 5. A router according to one ofclaims 1 and 2, wherein the user identifier is a SIP URI, the terminalidentifier is the IP address of the communication terminal, and therouter identifier is the IP address of the router.
 6. A router accordingto one of claims 1 and 2, the router being disposed on the borderbetween a Differentiated Service (Diff-Serv) network and a networkconnected to the communication terminal.
 7. A SIP server for managingthe Quality of Service type of each user and for instructing a routerserving a communication terminal to perform Quality of Service controlin accordance with the Quality of Service type of each user; the SIPserver being used in a network system comprising the router, the routerserving a communication terminal which sends a REGISTER messageincluding a user identifier and a terminal identifier to be used or acommunication terminal which sends, in response to an instructionmessage given for authentication, a REGISTER message including a useridentifier, a terminal identifier, and a router identifier included inthe instruction message, and performing Quality of Service control foreach user under an instruction from a server; the SIP server comprising:a table for storing a terminal identifier of the communication terminal,a router identifier of the router serving the communication terminal,and a certain Quality of Service type, in association with the useridentifier; means for analyzing a received message and determiningwhether the message is a REGISTER message; means for extracting a useridentifier, a terminal identifier, and a router identifier, if themessage is a REGISTER message, from a REGISTER message generated whenthe router has added the router identifier of the router to the REGISTERmessage including the user identifier and the terminal identifier givenby the communication terminal or from a REGISTER message sent from thecommunication terminal in response to an instruction message to whichthe router has added or updated the router identifier, sent from theserver to the communication terminal, for referencing the table inaccordance with the extracted user identifier, and for updating theterminal identifier and the router identifier associated with thecorresponding user identifier to the extracted terminal identifier andthe extracted router identifier; and means for instructing the routeridentified by the updated router identifier to perform Quality ofService control in accordance with a Quality of Service type associatedwith the user identifier or the updated terminal identifier, withreference to the table.
 8. A network system comprising: a router forserving a communication terminal which sends a REGISTER messageincluding a user identifier and a terminal identifier and for performingQuality of Service control for each user under an instruction from aserver; and a SIP server for managing the Quality of Service type ofeach user and for instructing the router serving the communicationterminal to perform Quality of Service control in accordance with theQuality of Service type of each user; the router comprising: means forjudging whether a received packet or a received message is a SIPmessage; means for analyzing and determining whether the message judgedto be an SIP message is a REGISTER message, for adding the routeridentifier of the local router to the REGISTER message including theuser identifier and terminal identifier given by the communicationterminal if the message is a SIP message and a REGISTER message, and fortransferring the REGISTER message with the router identifier added tothe SIP server so that the terminal identifier and router identifierstored in association with the user identifier are updated in the SIPserver; means for receiving a Quality of Service control instructioncorresponding to the Quality of Service type associated with the useridentifier or the updated terminal identifier, from the SIP server; andmeans for performing Quality of Service control for each user under thereceived instruction; the SIP server comprising: a table for storing aterminal identifier of the communication terminal, a router identifierof the router serving the communication terminal, and a certain Qualityof Service type, in association with the user identifier; means foranalyzing a received message and determining whether the message is aREGISTER message; means for extracting a user identifier, a terminal,identifier, and a router identifier, if the message is a REGISTERmessage, from a REGISTER message generated when the router has added therouter identifier of the router to the REGISTER message including theuser identifier and the terminal identifier given by the communicationterminal, for referencing the table in accordance with the extracteduser identifier, and for updating the terminal identifier and the routeridentifier associated with the corresponding user identifier to theextracted terminal identifier and the extracted router identifier; andmeans for instructing the router identified by the updated routeridentifier to perform Quality of Service control in accordance with aQuality of Service type associated with the user identifier or theupdated terminal identifier, with reference to the table.
 9. A networksystem comprising: a router for serving a communication terminal whichsends, in response to an instruction message given for authentication, aREGISTER message including a user identifier, a terminal identifier tobe used, and a router identifier included in the instruction message andfor performing Quality of Service control for each user under aninstruction from a server; and a SIP server for managing the Quality ofService type of each user, for instructing the router serving thecommunication terminal to perform Quality of Service control inaccordance with the Quality of Service type of each user, and forsending an instruction message for authentication to the communicationterminal; the router comprising: means for judging whether a receivedpacket or a received message is a SIP message; means for analyzing anddetermining whether the message judged to be a SIP message is aninstruction message, for adding the router identifier of the localrouter to the instruction message or updating the router identifierincluded in the instruction message to the router identifier of thelocal router if the message is a SIP message and an instruction message,and for transferring the instruction message including the added orupdated router identifier to the communication terminal so as to makethe communication terminal send a REGISTER message and to update theterminal identifier and the router identifier stored in association withthe user identifier in the SIP server; means for receiving a Quality ofService control instruction corresponding to the Quality of Service typeassociated with the user identifier or the updated terminal identifier,from the SIP server; and means for performing Quality of Service controlfor each user under the received instruction; the SIP server comprising:a table for storing a terminal identifier of the communication terminal,a router identifier of the router serving the communication terminal,and a certain Quality of Service type, in association with the useridentifier; means for analyzing a received message and determiningwhether the message is a REGISTER message; means for extracting a useridentifier, a terminal identifier, and a router identifier, if themessage is a REGISTER message, from a REGISTER message sent from thecommunication terminal in response to an instruction message to whichthe router has added or updated the router identifier of the router,sent from the server to the communication terminal, for referencing thetable in accordance with the extracted user identifier, and for updatingthe terminal identifier and the router identifier associated with thecorresponding user identifier to the extracted terminal identifier andthe extracted router identifier; and means for instructing the routeridentified by the updated router identifier to perform Quality ofService control in accordance with the Quality of Service typeassociated with the user identifier or the updated terminal identifier,with reference to the table.